It is important in some environments to ensure that doors into enclosures, such as cupboards, cabinets, boxes, drawers, or rooms, are not left open and unattended. For example, in the medical environment, drug cupboards and drug trolleys need to be used unimpeded for periods of time by staff but must not be left accessible without a member of staff present. On a busy hospital ward, it is very easy for a drug cupboard or drug trolley to be accidently left open and unattended and this has led to theft of controlled substances. This is highly undesirable and a balance has to be found between the practical use of a drug cupboard or drug trolley and securing the contents of these enclosures.
There are several types of device that have been used to secure doors and entranceways, however, most of these devices relate to unauthorised access rather than ensuring that doors are not left open and unattended. For example, U.S. Pat. No. 5,281,952 describes a device that allows an authorised person to determine if an unauthorised person has accessed a room. The device disclosed therein is triggered by light and, if an unauthorised user enters the room, the device will emit an audible alarm for a pre-determined amount of time. This device is one of many devices that detect light, movement, or temperature changes to determine if a door has been opened. However, this type of alarm is not suitable in every environment and for every situation. As stated above, in the medical environment, drug cupboards and drug trolleys need to be used unimpeded for periods of time by staff on hospital wards and, in such circumstances, an alarm that sounds constantly when the door is opened is highly undesirable.
Another approach is described in GB 2283603, where the device disclosed therein consists of an alarm unit and a magnet. When the alarm unit and magnet are separated for more than ten seconds, the alarm unit emits a sound. Again, this is not suitable in many environments and this approach is not useful for an enclosure that needs to be used unimpeded for potentially long periods of time.
Yet another example is a refrigerator alarm. Many refrigerators, for example by the Samsung group, have an alarm which is time based to remind users to close the door if left open for a predetermined time. This is helpful under most circumstances however can cause annoyance at times when the user wishes to leave the door open for a prolonged time, for example whilst transferring a weekly load of provisions into the refrigerator.
One device specifically designed to secure drug cabinets is the Controlled Drug Cabinet Alarm as sold by the FPD Group. This alarm is activated when the cabinet door is unlocked and an external red warning light is displayed to alert a user. After a pre-determined period of time a warning alarm or beep sounds. A disadvantage of this device is that the alarm will sound even if the user still requires the cabinet door to be open. Also, in order to turn off the alarm, the cabinet door would have to be closed which can lead to an inefficient use of time for the user if they still require access to the cabinet and would need to immediately reopen the doors.
Another device that calls a user's attention to an open drugs cabinet is the Nurse Station Unit made by Wandsworth. This device has a light provided on a control panel which indicates when the door of a drug cabinet has been opened. This could easily be missed by a busy nurse and also has the disadvantage of not indicating if the drugs cabinet is actually in use.